﻿1056 Notices respecting Neiv Books. 



distinction between pressure, as gauge or absolute, as he would be 

 compelled on changing from the uon-condensing locomotive to 

 the condensing marine engine, or in any therm odynamical calcu- 

 lations. In the high pressures of Internal Ballistics of Artillery, 

 the difference may be disregarded as unimportant. But it is 

 strange to read in an elementary text-book of this neglect, when 

 the author is employing his favourite absolute dynamical units in 

 Hydrostatics, and speaks of an atmospheric pressure of about 

 seventy thousand poundals on the square foot as something of 

 trifling account. 



On the M.T.S. system with g = 9-81, m/s 2 the absolute unit of 

 force would be about the heft of 102 kilogrammes, and an atmo- 

 sphere of one kg/cm 2 , or 10t/m 2 would be expressed by 981 in 

 M.K.S. units. 



Our artillerist reckons his pressure in the ton/inch 2 , of about 

 150 atmospheres. A normal pressure of 20 tons/inch 2 would be 

 3000 atmospheres, or 3 million M.T.S. units ; and here Halsey 

 would begin to protest. The C.T.8. system (centimetre-tonne- 

 second) could reduce this to 300 units, say 3t/cm 2 in the 

 gravitation unit the artillerist would employ in a measurement 

 of Force, and so on in a convenient scale for record and cal- 

 culation. 



It is when we come to Electro-Magnetic measurement we 

 find the powers of 10 require such careful attention, and a 

 system must be selected of universal acceptance in broadcasting 

 the theory. 



A Comprehensive Treatise on Inorganic and llieoretical Che- 

 mistry. By Dr. J. W. Melloh. Vol I. pp. xvi + 1065. 

 Yol. II. pp. viii + 894. (London: Longmans, Green & Co. 

 1922.) £3 3s. net each vol. 



Dr. Mellob has undertaken a very heavy task in attempting to 

 w 7 rite siugle-handed a Comprehensive Treatise on so vast a subject 

 as is now covered by the title 'Inorganic and Theoretical 

 Chemistry/ The two volumes of the Treatise which have been 

 issued furnish abundant evidence of the special qualifications 

 which Dr. Mellor has brought to his task, and of the skill and 

 industry with which he has marshalled the data with which the 

 volumes are so well stored. But whilst the competence and skill 

 of the author are beyond dispute, the magnitude of the work 

 which he has undertaken carries with it certain obvious dis- 

 advantages. Thus, in order to cope with the difficulty of bringing 

 even a single volume to completion, instead of spending his whole 

 life in keeping his information and indexes up to date, the author 

 has been obliged in certain instances to adopt rather drastic 

 methods of treatment, by resolutely closing down some sections 

 of the book in which new information is being gathered so quickly 



